SU1659713A1 - Method for measuring water discharge rate in open water stream with prismatic bed - Google Patents

Abstract

The invention relates to agriculture and can be used in a water distribution and water accounting system on open streams with a prismatic channel. The aim of the invention is to improve the accuracy of determining the costs of open streams with a prismatic channel. In the original channel, a section of length L (20-25) b, where b is the channel width (with a reverse inclination of 10 br - (0.001-0.003), and the depths of the flow are measured in two flaps located at a distance U from each other (10-15) b, and the flow rate is determined by the formula analytical by solving a differential equation of a non-uniform steady-state smoothly changing water flow regime 1 ill.

Description

The invention relates to agriculture and can be used in a water distribution and water accounting system in open streams with a prismatic channel.

The aim of the invention is to improve the accuracy of determining the flow in an open watercourse with a prismatic channel.

The drawing shows a plot of the measuring channel with variable slopes.

The entire channel has a slope i 0. On the segment of the channel L (20-25) b, where b is the width of the channel along the bottom, a section with a slope of sample 0 is arranged. It is recommended to take 1 rev - - (0.001-0.003). In the segment L, the segment Li (10-15) b is selected, at the beginning and end of which the gauging stations are established

k and f. On these gauges, depth gauges 1 and 2 are installed, about which they coincide with the bottom mark in these sections. The depth at k is rtK, and at f, hf.

The sequence of operations in determining the flow rate of the proposed method is as follows. First, the depth gauges 1 and 2 (Fig. 1) are used to determine the depths hk and hf in the respective sections k and f, Then, with known channel and flow parameters (U, 1obr, n, b, m, etc.), TC values of Ck, Cf, Rk, Rf; next, the values of the averaged S, P averaged values and the parameter A are found. Substituting the found and known values in formula (1), the sought-for flow is calculated using the formula

About SP Yu

VI with

which is an analytical solution of a differential equation of a steady-state, non-uniform, slowly changing water flow;

1ob.2 (1 eA)

Q

(one)

And with fifjlbi ("iJ Parameter A, which is included in equation (1), is determined by the formula

2frf-xk) (2S + 1) I, nfuЈhf, Rf + hk 1obR og hk

where8

-Bk hk, bf hf

r-l-ljr Mobr dT

kCiRk Ci are the averaged values of the dimensionless quantities Bh h in the considered section. th

Xf - xk Li - distance between sections k and f, m;

Q - the required flow rate, m3 / s;

hf, hk - water depths in the sections f and k, m;

a) k, a) f - the area of the living cross section of the flow i in the sections k and f, m;

f Ckt Cf are the Chezy coefficients in the ranges k and f, cm;

Rk, Rf is the hydraulic radius in cross sections k and f, m;

1 obr reverse slope of the channel bottom; a is a speed factor of 1.1;

g — free fall acceleration, m2 / s;

e is the base of the natural logarithm.

The invention provides the versatility of the method for determining the flow rate, which consists in the possibility of determining the flow rate in any mode of a steady-state slowly varying water flow regime by creating a drop-off curve in the subcritical mode kk and H (Fig. 1) and a backwater curve in the supercritical flow mode reverse slope | 1pr 0) between the indicated channel sections; improving the accuracy of determining the flow rate due to the use as a calculation formula of the ratio, which is an analytical solution that has established a smoothly changing

water flow regime.

Claims (1)

The invention The method of determining the flow of water on an open waterway with a prismatic node, including the measurement of the depth in two channel sections with subsequent calculation of flow rate by the difference of depths in these section sections with known channel sizes, characterized in that, in order to improve the accuracy of flow measurement, depth measurements are made on a section of length L (20-25) 5, made with a reverse inclination 0br - 4Q..003), at a distance equal to Li (tO-15) b, and the flow rate is determined by the formula Q, / J ,, f -0. (I) (1st HJlt) where the parameter A is determined from the expression - ((- | 1-) P | g + hf 2 VCe Rk C Rf )   bBkhk, Bfhf, (). - the averaged values of dimensionless values -; (a C2R xf- Xk Li is the distance between sections k and f, m; b — channel width, m; Q - the required flow rate, m3 / s; hk, hf - water depth in the sections k and f, m; O) k, u f are the areas of the living section of the sweat in the ranges k and f, m; % Shezy coefficients in cross sections k and f, m1 2 cm; 1pp is the reverse slope for the channel; a is a speed factor of 1.1; about - acceleration of free fall, m / s e is the base of the natural logarithm, Rk, Rf is the hydraulic radius in cross sections k and f, m.  + ISJ S L () - &